Hey all, new Damm-kota owner and new to the forum as well. I am trying to figure out a few issues with my 2002 3.9 2wd auto.

1st issue: It has what feels like a miss on one cylinder, but hasn't thrown any codes. It occurs at 600 - 1600 rpm, and doesn't change when the truck is cold or hot.

At all times warm or cold, when I go from idle to WOT (stomping the gas) it will fall flat on its face for about 1 to 2 seconds, cough and sometimes backfire through the pipe, then it catches and revs like it should with no loss of power.

I am thinking I should clean the upper O2 sensors and/or look for a lazy or partially clogged injector. Beyond that, I dunno.

What I have done to her so far:
New plugs, wires, rotor, cap (brass contacts), oil n filter, MAP and TPS, cleaned IAC and TB, seafoam in the tank and oil before change. Also replaced both upper control arms and lower ball joints, tie rod ends, and swaybar links because they were all rotted out.

2nd issue: Transmission makes a groaning noise in reverse only, and only when cold. It sounds like the power steering pump groaning. All forward gears work and shift as they should and reverse works, its just noisy. I have read that this is a normal thing on some Dodges, just wondering if that holds true for the 42re.

I will be doing a filter and fluid change tomorrow and the service schedule calls for adjusting the bands also.Should I do this if it is shifting good? If so, I am looking for some specs or a walk-through on how to do that.

Any suggestions yall can give is greatly appreciated.

The truck has low miles, but PO treated it like a redheaded stepchild. (neglected, beaten, and told that it was ugly) It also sat for 6yrs with minimal use and what looks like no maintenance.
I am trying to convince her that life is really worth living now..

 

In the old days of points and condensers, I would suggest checking the timing for that stumble problem, but these days I don't know if that would be a viable suggestion. I guess that theoretically the timing shouldn't change if there's no points to wear out but on the other hand it might be a good start. After that I'm lost.

 

Welcome to the forum Tony.

You can't clean O2 sensors. If you have a lot of miles on them just replace them - and do NOT use Bosch. Use NTK or Denso. Dakota's hate Bosch.

You changed the MAP and TPS sensors. What did you use for parts? OEM is preferred. Lately there have been LOTS of bad parts out there. I'd be suspicious of the TPS.

It could be ignition related. The cam position sensor in the distributor or even the crank position sensor. Still, you should toss a code. If you have a scanner that reads live data it might help you determine what is really going on.

Make doubly sure there are no vacuum leaks around the manifold. The plenum plate is a known issue. In a fuel injected car the IAC is really just a calibrated vacuum leak so having another leak can cause problems even though it idles just fine.

I'd start with a fluid/filter change on the tranny. Yes, some do make noise but the fluid/filter can't hurt. It won't hurt to adjust the bands.

 

Definitely use Mopar parts.

 

I have used NAPA's Belden? line for some parts, others I have ordered from Rock Auto. I still haven't done the tranny fluid yet, had to work today and probably tomorrow, but the trans filter I got from NAPA. I had read that the aftermarket filters for the tranny's might have bad check valves but NAPA's should be ok. Should I take it back for a Mopar?

For the TPS and the MAP, I got those from RockAuto, and they aren't MOPAR, but when I switched them out, there was no change at all. I kept the old sensors which I believe are original from the factory, so if I have to, I can switch them back.

I also arrived at the conclusion that I needed to get a scanner to really pinpoint what is happening and why. I ordered an interface for my laptop and it comes with software that reports and records live data, so until that comes in, I think I will wait.

Also, how long mileage-wise does it usually take to spit out a code? I hesitate to drive it much until I can be confident that it won't leave me stranded. But if I need to drive it more to get the computer to pop out a code, then I will.

 

Hopefully the live data will help identify the problem but don't rule out a mechanical issue which may not be apparent on the data. Check for vacuum leaks anyways.

How long until the code appears depends upon the code. Some pop up by cycles, others at key on, others when detected.

The filter issue is primarily a 45RFE (4.7) problem. I'm not familiar with the NAPA filter for your application.

 

Well, I am still waiting on shipping for the scanner.. $@#& cheapo ground shipping..

The truck seems to be smoothing out a bit now, perhaps the computer just needed some time to learn the new parts. I am going to hold off doing a reset on the computer until after I get the scanner though. (don't want to flush any ghost codes or pending codes if it has them).

Also looked down into the intake and saw what looked like a fine misting of oil, no puddles. Then checked the PCV valve and it rattles. I may just replace it because it's cheap.

couldn't find any vacuum leaks and surprisingly, most of the hoses are still soft and pliable. (truck only has 53,000 on it)

 

Well, I got my scanner in today and hooked it up. No codes, no pendings, and no stored snapshots from previous codes.

There are a few numbers that looked a bit off so I will list them, (final numbers are from a snapshot I took while running.)

right after startup, I noticed the long term fuel ratios were at -13 and -8 (Rich?) they settled to -2.34 and - 3.91 for bank 2 when the truck hit full operating temp.

short term fuel trims were .78 for bank 1 and 3.91 for bank 2 when warmed up. they were bouncing around a bit and generally looked similar to each other.

the IAT started at 88 degrees cold and went to 174 degrees after full warmup.

intake manifold absolute pressure was at 13.78 psi at idle.. Low? min was 4.6 and the mean was at 5.1

both upstream o2 sensors ended up at .82 and .78 at temp and i didn't see them do anything funny when I revved it to 2000 rpm.

Tested the tps before starting and the readings were in % instead of volts. It went from 9% at idle to 65% at WOT.

anything jumping out at you guys? Is the Manifold absolute pressure reading within specs? I don't know where these numbers should be so I am in the dark.

 

The map sensor value is probably pretty close. It'll vary due to your elevation and the atmospheric pressure.

Yes, the fuel trim is showing rich. I'm curious as to why bank 2 is "more" rich. The long term fuel trim is the "better" average value.

I'd probably start by replacing the O2's. They don't last forever. Use NTK or Denso ONLY!!! No Bosch.